MPLAB SIM. MPLAB IDE Software Simulation Engine Microchip Technology Incorporated MPLAB SIM Software Simulation Engine

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1 MPLAB SIM MPLAB IDE Software Simulation Engine 2004 Microchip Technology Incorporated MPLAB SIM Software Simulation Engine Slide 1 Welcome to this web seminar on MPLAB SIM, the software simulator that comes with the free MPLAB Integrated Development Environment, or IDE. My name is Darrel Johansen and I m a manager for Development Systems at Microchip Technology. This 20 minute seminar will focus on MPLAB SIM, and will demonstrate how this tool can be used to develop and debug code for Microchip microcontrollers. 1

2 MPLAB SIM WebSeminar Agenda MPLAB SIM is one debug engine used by MPLAB IDE MPLAB SIM has debug features similar to other debug engines MPLAB SIM has some unique debug features MPLAB SIM can have input stimulus signals and can log register outputs to files 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 2 This seminar will describe MPLAB SIM, one of the debug engines available for MPLAB IDE. It has similar features to other debug engines, allowing the engineer to switch from one to another without encountering a new learning curve. MPLAB SIM also has some unique debugging features that are not available in the hardware debuggers. In order to debug the operation of code with simulated external signals, input stimulus events can be created. And in order to measure how an application performs, registers can be logged to files, graphed and be subjected to further analysis. 2

3 Debug Engines MPLAB IDE Debugger MPLAB SIM MPLAB ICD 2 MPLAB ICE 2000 MPLAB ICE Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 3 The other debug engines are hardware devices, while MPLAB SIM is a software program, running on your PC. MPLAB SIM provides many of the same features as in-circuit emulators and in-circuit debuggers. The difference is that both in-circuit emulators and incircuit debuggers allow the code to be run on actual silicon, and also allow a target application hardware to be functional while being debugged. MPLAB SIM has features to simulate hardware interaction with other signals and devices, and since it is running as software on the PC, it has complete information about the internal state of the simulated chip at each instruction. This is a little different from the hardware debuggers because, while they are running code at full speed, they typically cannot monitor all registers and all memory in real time. Both MPLAB SIM and the hardware debuggers can do the traditional functions of debuggers, but due to their differences, they can have unique features of their own. This presentation will identify the functions and features of MPLAB SIM. 3

4 Debugger Basic Functions: Reset Target Execute Code Halt Code Examine/Modify Registers/Memory Single-Step Code 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 4 The debugger is a part of MPLAB IDE, and whether you are using MPLAB SIM, MPLAB ICE or MPLAB ICD 2, most operations are exactly the same. This allows you to develop code using the simulator, then when your hardware is ready, you can use a hardware debugger to further test your code in practice without having to learn how to use a new tool. These are the basic debug functions: Reset the target, in order to restart the application Execute the code so the program can be tested to verify it functions as designed Halt the code at breakpoints While halted at breakpoints, memory and variables can be examined and modified to analyze and debug the application code To closely inspect how code executes, each instruction can be Single stepped. This allows the engineer to go through code one instruction at a time while monitoring affected variables, registers and flags. Single stepping essentially zooms in on code to ensure that it operates properly in complex and critical sections with ranges of variable values and under various test conditions. 4

5 Advanced Functions: Watch Points Trace Buffer Stopwatch Complex Breakpoints Debugger Correlate Machine Code Execution and Memory Contents with High Level Language Source 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 5 Most debuggers also have additional features to help analyze and debug the application. Some of these are listed here: Watch points group and monitor selected variables and memory locations into a convenient, custom readout. Trace buffers capture the streams of instructions executed and reveal the contents of changing register values. A Stopwatch can time a section of code. Routines can be optimized, and critical code timing can be accurately measured and adjusted. Complex breakpoints offer a method for establishing breakpoints or for gathering data in the trace buffer based upon multiple conditions. Simple breakpoints allow setting breakpoints in the source code or anywhere in program memory. Complex breakpoints allow getting a breakpoint on a condition such as, after the main routine called RefreshDisplay executes then wait for subroutine ReadTemp to execute. Then break if the variable named Temperature is greater than 20. Complex events can even be constructed to count events, so that a subroutine would have to be executed 15 times before it starts looking for a value on a pin or in a register. This kind of breakpoint allows you to describe the condition where your code misbehaves, then gets a breakpoint or traces code at that condition. This is usually a faster way of finding bugs than simply setting simple breakpoints and stepping through your code. Finally, most advanced debuggers allow you to correlate the execution of the application on the target with the source code. This allows you to single step through C source code, even though each C statement may generate many lines of machine code. Likewise, memory storage in file registers is correlated with the variables you use in your program. So if you have a floating point number that spans multiple machine file registers, you can monitor the multiple file register contents in a Watch Point to display the value in floating point representation. 5

6 Simulator Runs as a software program on PC Runs at a speed determined by PC speed, simulation activities, operating system tasks, but times events based upon simulated operating frequency. Simulates core CPU, memory, many peripherals Responds to simulated inputs called stimulus signals. Can log outputs to files for further analysis Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 6 MPLAB SIM is a simulator, and as a result it has certain characteristics that make it a unique debug engine. In modern Windows based PCs, many things are happening in the background --other programs may be running, hardware may be communicating to the PC, and so on. So the speed of the simulation is determined by how fast your PC executes, the complexity of the current simulation, and the number of other tasks executing on your PC. Currently the maximum speed of MPLAB SIM is on the order of 10 MIPS, or 10 million instructions per second. This will be affected by how many other things are being done by your PC, by the code the simulator is running, and by the other tasks that the simulator is performing. The simulator simulates the operation of the core CPU and it s internal registers, memory, and many of it s peripherals. In order to test the application on the simulator, stimulus signals can be applied to pins and registers. To evaluate performance, the simulator can log changing registers to files for further analysis. 6

7 MPLAB IDE Desktop 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 7 This is the MPLAB IDE desktop when it is first started up. There is a standard menu across the top a tool bar below this, a blank Workspace window, and a status bar on the bottom. 7

8 MPLAB IDE Select Debug Engine 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 8 MPLAB SIM is selected as our debug engine from the Debugger menu. Note the other functions on the debug menu, such as Run, Step, and Breakpoints. We ll look closer at some of these other options soon. 8

9 MPLAB SIM 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 9 Once a debug engine is selected, the toolbar is appended with some new icons for running, halting, single stepping, and resetting the target. 9

10 MPLAB SIM 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 10 The Status bar now shows some additional information as well. MPLAB SIM shows as our current debug engine. The simulated processor is listed, in this case the PIC18F452, then the program counter, the W register, the current state of the internal CPU flags and the current selected file register bank. 10

11 MPLAB SIM 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 11 Operations can be selected in multiple ways depending upon how you like to work. You can select functions from: The toolbar icons, the menus, or the hot keys listed on the menus can be used to execute the debug functions. Note that some functions are a little more complex, such as Reset, which actually has four types of reset actions. Once MPLAB SIM is established as the debug engine, whenever a project is built, it is automatically loaded into the simulator s program memory to be run and tested. Various debug windows become available <click> 11

12 MPLAB SIM Source Code Window 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 12 One debug window is the source code window. This is actually the editor, and breakpoints can be set by clicking on a line with the right mouse button. Single stepping with the source code window in focus will single step through the C source lines. Since you are in the editor, changes can be done quickly, and the project can be rebuilt. 12

13 MPLAB SIM Program Memory Window 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 13 The Program Memory window shows the machine code that will be executed by the simulator. Single stepping with this window in focus will allow you to step through each machine instruction. 13

14 MPLAB SIM Disassembly Window 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 14 Another window, called the Disassembly Listing window shows high level source code interspersed with machine code generated by each C statement. 14

15 MPLAB SIM Watch Window 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 15 You can also open up a watch window and drag the variables from your program to see the contents as you break and single-step through your code. While debugging, other windows are available to view register memory, stack memory, and non-volatile data memory areas. 15

16 MPLAB SIM Stopwatch 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 16 The Stopwatch dialog can time sections of code as they run on the simulator. The Stopwatch calculations are based upon the instructions executed and the setting entered for the Processor Frequency. The processor frequency is set to 20 Mhz in this example. From the number of instruction cycles executed, the total time is calculated. This is the time it would take to run on a real chip. 16

17 MPLAB SIM Stopwatch 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 17 The stopwatch has two pairs of readouts, one tells the total simulated clock cycles and the corresponding execution time <click> 17

18 MPLAB SIM Stopwatch 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 18 and the other can be zeroed out, to make a measurement from one breakpoint to the next. 18

19 MPLAB SIM 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 19 The stopwatch is one way to measure time in the simulator, but there is another: The trace buffer records instructions when they execute and puts a time stamp on each instruction. After you capture events in the trace buffer, you can time them. The trace buffer has the advantage that it can capture large amounts of data selectively and each instruction has a time stamp. You can capture an interrupt routine, for instance, and then easily calculate the time between interrupts and the total time each interrupt took to execute. 19

20 Simulation Engine Core CPU Core and Memory 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 20 A block diagram of the simulator might look like this. At the center is the simulation of the CPU core with the various program, file and data memory areas; the instructions; the stack; the program counter and the status flags of the device being simulated. 20

21 Simulation Engine CPU Core and Memory Pins Peripherals Registers 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 21 Simulation includes pin inputs and outputs as well as many of the other peripherals. The peripherals communicate to the application through special function registers. 21

22 Simulation Engine CPU Core and Memory Stimulus Pins Peripherals Registers 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 22 A complex Stimulus Generator simulates signals that can be applied to the device under simulation. The stimulus generator can send signals to pins or to registers in the simulator. 22

23 Simulation Engine CPU Core and Memory Stimulus Pins Peripherals Log Registers 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 23 The activity of the simulator can be sent to a Log file for later analysis. This is done by using either the USART as a communication device for inputs and outputs, or by using the register log feature. Both stimulus and logging activity can be driven either by execution at a specified program counter address or by sequencing on demand. On demand means that whenever that register is read by an instruction, a value is read from or written to a list, then advanced to the next position in the list. 23

24 Stimulus Sources Manual Cyclic Sequence 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 24 There are three types of Stimulus sources for MPLAB SIM: Manual triggers are changes in digital signal levels caused by clicking on a button with a mouse. These allow you to simulate the action of closing a switch, or pulsing a pin. A Cyclic stimulus generates a repeating waveform, either a for a predetermined length of time, or continuously. Sequential data is data that can be applied to pins, registers, or bits in registers from a list. A list for sequential data can be entered in a dialog or it can come from a file. 24

25 Stimulus Controller 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 25 Here is the Stimulus Controller for MPLAB SIM. In this dialog, you can select actions to apply to a pin and then, when your program is running, you can press the associated Fire button to the left of the pin name to activate that signal. 25

26 Stimulus Controller: Manual 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 26 For instance, we could set up a pulse to occur on PORTA pin RA3. Here, when we press the Fire button, the simulated signal on RA3 will pulse high for 8 microseconds. 26

27 Stimulus Controller: Manual 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 27 More actions can be added. Here two more are shown, one to force the INT0 pin low when we press the fire button, and one to toggle the INPUT pin for the Timer/Counter. A Toggle Action will alternate between setting the pin high and low each time the Fire button is pressed. 27

28 SCL Workbook: Pin / Register Actions 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 28 For more complex stimulus control, actions are entered in the SCL Workbook. SCL stands for Stimulus Control Language, but with the graphical user interface of MPLAB, all stimulus events can be set up with these easy graphical dialogs. Once the events are described in the SCL Workbook, they are compiled into an SCL file that can then be loaded into the Stimulus Controller. There are five tabs in this workbook. 28

29 SCL Workbook: Pin / Register Actions 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 29 The first tab in the SCL Workbook uses a list of times and signals to be applied to pins and registers. For instance, we can set up a series of events to happen on pin RA1. Here 15 microseconds after the program is reset and started, the pin RA1 will go high. Then at 35 microseconds after the start of the program pin RA1 will go low. We can add other steps and signals to this dialog. 29

30 SCL Workbook: Pin / Register Actions 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 30 Here sequences of events are applied to pin RA1, PORTB, the Timer interrupt flag, and to the A/D buffer. The list of values under the column labeled PORTB are 8-bit values that will be applied to all eight pins of PORTB at the times entered down the left column. The next column is a list for a signal connected to the Timer0 interrupt flag, an internal register. The two columns on the right allow the A/D buffer to be set to a sequence of 10-bit values. 30

31 SCL Workbook: Advanced Pin / Register 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 31 The second tab in the SCL Workbook, the Advanced Pin/Register tab, provides conditional control over events. 31

32 SCL Workbook: Advanced Pin / Register 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 32 Here a condition must occur before the stimulus is activated. The condition is described in the bottom section. The condition is gating the event to happen 2 microseconds after pin CCP1 goes low. When that occurs, a value of 55 will be applied to PORTB. 32

33 SCL Workbook: Advanced Pin / Register 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 33 Other events can be described on subsequent lines. The event can be a 1x event, which means that it will occur only once, or it can be a Continuous event, meaning that will happen every time the associated condition occurs. Here a second event happens each time TMR2 reaches a value of 84. When this happens, PORTB will change to a value of 10, and the INT1 pin will go high. There is a 10 microsecond re-arm delay. This prevents this event from happening sooner than 10 microseconds after its last firing. 33

34 SCL Workbook: Clock Stimulus 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 34 The Clock Stimulus tab of the SCL Workbook generates repeating digital waveforms. 34

35 SCL Workbook: Clock Stimulus 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 35 Four waveforms are entered here. The first called istrobe holds the RA5 pin low for 10 instruction cycles, then goes high for 15 instruction cycles. It starts immediately, and never stops. A Comments column and the Label column are user-defined labels for this dialog, and are free-form, allowing any text entry. The label is arbitrary, simply for tagging the lines in this dialog with a descriptive name. Line two describes a waveform that will be applied to RA6. RA6 will start out low, stay low for 100 cycles, then go high for 150 cycles. It will not start until the program counter reaches the routine called test. It will begin cycling and will stop when the program counter reaches a routine labeled done. Line three describes a stimulus event depending upon the INT1 level. When INT1 goes low the signal on RC0 goes low for 2 cycles then high for 50 cycles. It will continue cycling until INT1 goes high. The last line generates a signal on RC3 that starts low, stays low for 3 cycles, then goes high for 30 cycles. It starts this operation only after 1500 cycles have elapsed since the program was reset, and will stop 1800 cycles after the program started, being active for only those 300 cycles. The last two tabs, Register Injection and Register Trace will be used in the following example. 35

36 Simulated Process 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 36 For this next example, two waveforms will be added together and sent out PORTB, possibly to go to a Digital to Analog converter. The diagram represents the two waveforms on the left being applied to to A/D pins of the microcontroller chip in the middle. The 8 Pins from PORTB go out to some device that will convert them back into analog signals. 36

37 Code: Add Two Waves 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 37 This is the entire program that will be used to add the two waves that are coming in to the A/D converter from two pins, then output that sum to PORTB. 37

38 Add Two Waves Code while (1) { if(adcon0 & 0x08) { ADCON0 &= 0xF7; // select AN0 ADCON0 = 0x04 ; // set GO bit Delay(); input0 = ADRESL; // read AN0 } else { ADCON0 = 0X08; // select AN1 ADCON0 = 0x04; // set GO bit Delay(); PORTB = (ADRESL + input0)/2; // add AN0 AN1 and scale } } 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 38 Here is just the essential code from the main routine. The code executes in this infinite loop, alternately getting inputs from pins AN0 and AN1. Line 2 looks at bit 3 of ADCON0 to see whether AN0 or AN1 was used in the last conversion, and switches to the alternate input pin. The A/D conversion is started by setting bit 3, the GO bit in ADCON0, then a delay is needed to allow conversion time before reading. The first wave is read in from AN0, and stored in the variable named input0. 38

39 Add Two Waves Code while (1) { if(adcon0 & 0x08) { ADCON0 &= 0xF7; // select AN0 ADCON0 = 0x04 ; // set GO bit Delay(); input0 = ADRESL; // read AN0 } else { ADCON0 = 0X08; // select AN1 ADCON0 = 0x04; // set GO bit Delay(); PORTB = (ADRESL + input0)/2; // add AN0 AN1 and scale } } 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 39 The next time through the loop, the else clause will execute, and input0 will be added to the A/D signal from AN1 and sent out PORTB. 39

40 Code: Add Two Waves Input File 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 40 A source file is made up containing the values for the waves being applied to the two A/D pins 40

41 Code: Add Two Waves Register Injection 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 41 The register injection tab of the SCL workbook allows us to set up the A/D conversion register to receive it s input from the data file, named waves.txt. The number will be interpreted as decimal values, will rewind starting over when the end of the file is reached and the values will be sent to the A/D conversion register on demand. This means that each time the A/D conversion register is read by our program, the next value in the file will be used. 41

42 Code: Add Two Waves Register Trace 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 42 In order to validate that the code is working, we use the Register Trace tab of the SCL workbook and set PORTB to be logged on demand, in other words, each time it is written to. The values will be sent as decimal number to the file named PORTWAVES.TXT. Now we generate the SCL file by compiling <click> 42

43 Code: Add Two Waves Attach SCL File 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 43 then open the Stimulus Controller and attach our SCL files. Now we can run the application. 43

44 Code: Add Two Waves Graph Output Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 44 After stopping the application, we have the results of our log in the file named PORTWAVES.Txt. We can open the file to look at it, then paste the values into a program like MATLAB or Excel to graph the wave. 44

45 dspic30f PIC18 MPLAB SIM Technology High Speed Many Peripherals Simulated Complex Stimulus and Output File Logging MPLAB C30 C Compiler printf() Support High Speed Many Peripherals Simulated Complex Stimulus and Output File Logging MPLAB C18 C Compiler printf() Support SOON! PIC10/12/16 High Speed SOON! Many Peripherals Simulated SOON! Complex Stimulus and Output File Logging SOON! 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 45 This has been a short demonstration of some of the powers of MPLAB SIM in conjunction with the C compilers, MPLAB C30 and MPLAB C18.. Currently the high speed and extensive peripheral simulation extend to the PIC18 and dspic microcontrollers. The dspic family has one additional stimulus feature: the ability to use printf() statements from MPLAB C30 to log output files. With printf() logging, reports can be generated with precise formatting, and with complex data types. All Microchip Technology microcontrollers are simulated in MPLAB, but only the PIC18 and dspic devices have these complex stimulus features, high simulation speed and extensive peripheral simulation. As this web seminar is being developed, MPLAB v6.60 is the latest release. This new simulation technology is being tested in the PIC10/12/16 series microcontrollers, and the printf() feature is being added to MPLAB C18. Be prepared to see the simulator get turbo-charged when these are implemented in future versions of MPLAB IDE and the MPLAB C18 compiler. 45

46 MPLAB SIM Summary MPLAB SIM is a free software tool to help debug code for Microchip microcontrollers MPLAB SIM simulates the CPU core, many peripherals, and the pins of the device MPLAB debugger uses MPLAB SIM as a debug engine to test application code MPLAB SIM can perform time measurement of code Stimulus signals can be applied to pins and registers to test an application Logged events can be used to validate and analyze applications 2004 Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 46 To recap the features of MPLAB SIM: MPLAB SIM and MPLAB are available free for download from It supports all current PICmicros and dspic microcontrollers made by Microchip Technology, and as new processors are developed, MPLAB SIM is extended to support them. MPLAB SIM simulates the CPU core, the various memory areas, many peripherals and the pins of the microcontroller. MPLAB s debugger functions use MPLAB as one of several debug engines to test code. The other debug engines are in-circuit emulators and in-circuit debuggers. MPLAB SIM can accurately measure code timing using the Stopwatch or the time stamp feature of the Trace Buffer. Stimulus signals can be applied to pins and registers. These signals can be triggered manually, can be set up as lists of events, can be repetitive waveforms, and can be activated by complex conditions. 46

47 Download FREE Microchip Technology Incorporated An introduction to MPLAB Integrated Development Environment Slide 47 And did we say that you can download MPLAB IDE which includes MPLAB SIM and all these features free from the Microchip Web site? Thank you for your time. 47